Reflow soldering device

ABSTRACT

In a reflow soldering apparatus comprising a conveyor  4  to transport circuit boards  5  mounted with electronic components into multiple chambers  1, 2  and  3,  and fans  6  installed in the chambers  1, 2  and  3,  the centers of the impellers in the adjacent fans  6  are not on a single perpendicular plane along the transport line of the conveyor and arrayed offset to the left and right. This apparatus may also employ a structure wherein the centers of the impellers in the adjacent fans are not on a single horizontal plane and arrayed offset up and down. Further, it may also employ a structure wherein the fans are arranged with their rotation shafts inclined.

TECHNICAL FIELD

The present invention relates to a reflow soldering apparatus installedwith a conveyor to transport circuit boards mounted with electroniccomponents into multiple chambers, blowing means and heaters.

BACKGROUND ART

A reflow soldering apparatus solders electronic components on a circuitboard while transporting the circuit board on a conveyor through aheating chamber where soldering paste is heated and melted and a coolingchamber where the melted solder is cooled.

The reflow soldering apparatus is installed with a fan and a heater toperform reflow soldering of the electronic components using heated gas.A reflow soldering apparatus of this type generally has multiplepreheating chambers and reflow chambers in sequence along the transportline of the conveyor. A fan and a heater are installed in eachpreheating chamber and reflow chamber. The fan and heater are arrangedabove and below the conveyor. Gas heated while passing through a heateris guided by a blow guidance means installed in each chamber and blownout from many nozzle holes to heat and melt the soldering paste on theprinted circuit board mounted with electronic components on theconveyor.

In this reflow soldering apparatus, the fan has a vertical rotatingshaft and is installed in the center of each chamber. The fans arearranged in a straight line along the transport line of the conveyor(see for example Japanese Patent Publication No. 2002-134905).

When the size of the fan is enlarged to increase the fan power, theproblem occurs that the total length of the reflow soldering apparatusis increased by an increasing amount of the fan size, since these fansare installed in a straight line along the transport line of theconveyor.

In view of the above problems, the present invention has the object ofproviding a reflow soldering apparatus capable of employing a blowingmeans with a larger size without increasing the total length of theapparatus.

DISCLOSURE OF INVENTION

In the present invention, a reflow soldering apparatus comprising aconveyor to transport circuit boards mounted with electronic componentsinto multiple chambers, and blowing means installed in the chambers ischaracterized in that the centers of the impellers in the adjacentblowing means are not on a single perpendicular plane along thetransport line of the conveyor and arrayed offset to the left and right.

The blowing means may for example be arranged left and right in a zigzagpattern along the transport line of the conveyor.

The present invention may be comprised as follows. A reflow solderingapparatus comprising a conveyor to transport circuit boards mounted withelectronic components into multiple chambers, and blowing meansinstalled in the chambers is characterized in that the centers of theimpellers in the adjacent blowing means are not on a single horizontalplane and arrayed offset up and down.

The blowing means may for example be arranged above and below in azigzag pattern along the transport line of the conveyor.

The present invention may be further comprised as follows. A reflowsoldering apparatus comprising a conveyor to transport circuit boardsmounted with electronic components into multiple chambers, and blowingmeans installed in the chambers is characterized in that the blowingmeans are arranged with their rotating shafts inclined in the chambers.

In the reflow soldering apparatus having blowing means above and belowthe conveyor, the rotating shafts of the upper and lower blowing meansmay be arranged diagonally in different directions, or may be arrangeddiagonally in the same direction.

The present invention as described above, allows installing a blowingmeans with a larger size or in other words greater power withoutincreasing the total length of the reflow soldering apparatus. A reflowsoldering apparatus with both superior performance and a compact designcan therefore be provided.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a vertical cross sectional view showing a preferred embodimentof the reflow soldering apparatus of the present invention.

FIG. 2 is a vertical cross sectional view of a portion of the reflowsoldering apparatus cut at a right angle to the transport line of theconveyor.

FIG. 3 is an enlarged view of a portion of FIG. 1.

FIG. 4 is a horizontal cross sectional view of a portion of the reflowsoldering apparatus as seen from the conveyor side.

FIG. 5 is a horizontal cross sectional view of a portion of the reflowsoldering apparatus cut at the first wall.

FIG. 6 is a horizontal cross sectional view of a portion of the reflowsoldering apparatus cut at the second wall.

FIG. 7 is a perspective view showing a first and second casing memberconnected by a duct.

FIG. 8 is a vertical cross sectional view showing another preferredembodiment of the reflow soldering apparatus of the present invention.

FIG. 9 is a vertical cross sectional view of a portion of the reflowsoldering apparatus cut at a right angle to the transport line of theconveyor.

FIG. 10 is an enlarged view of a portion of FIG. 8.

FIG. 11 is a horizontal cross sectional view of a portion of the reflowsoldering apparatus and shows the first casing member.

FIG. 12 is a horizontal cross sectional view of a portion of the reflowsoldering apparatus and shows the second casing member.

FIG. 13 is a perspective view showing a first and second casing memberconnected by a duct of a short length.

FIG. 14 is a perspective view showing a first and second casing memberconnected by a duct of a long length.

FIG. 15 is a front view showing another preferred embodiment of thereflow soldering apparatus of the present invention.

FIG. 16 is a horizontal cross sectional view of a portion of the reflowsoldering apparatus.

FIG. 17 is a vertical cross sectional view of a portion of the reflowsoldering apparatus.

FIG. 18 is a perspective view showing a first and second casing memberconnected by a duct.

FIG. 19 is a vertical cross sectional view showing another preferredembodiment of the reflow soldering apparatus of the present invention.

FIG. 20 is an enlarged view of a portion of FIG. 19.

FIG. 21 is a cross sectional view taken along line A-A of FIG. 20.

FIG. 22 is a perspective view showing a first and second casing memberconnected by a duct.

FIG. 23 is a vertical cross sectional view showing still anotherpreferred embodiment of the reflow soldering apparatus of the presentinvention.

BEST MODE FOR CARRYING OUT THE INVENTION

A preferred embodiment of the present invention is described next whilereferring to the accompanying drawings FIG. 1 through FIG. 7.

A reflow soldering apparatus as shown in FIG. 1, is comprised of threepreheating chambers 1, two reflow chambers 2, and one cooling chamber 3which are arrayed in sequence along the transport line of a conveyor 4.Nitrogen gas is supplied into each of the chambers 1, 2 and 3 to preventoxidation of the solder. A printed circuit board 5 mounted withelectronic components is transported in sequence into each of thechambers 1, 2 and 3 by the conveyor 4. After the printed circuit board 5mounted with electronic components is heated at a predeterminedtemperature in the preheating chamber 1, the soldering paste is meltedin the reflow chamber 2, the melted solder then cooled in the coolingchamber 3, and the electronic components soldered onto the printedcircuit board. Nitrogen gas is used in this embodiment to provide thegaseous atmosphere within each of the chambers 1, 2 and 3, however airmay be used as the atmospheric gas.

The conveyor 4 makes a transport line arranged horizontally in a forwardpath in approximately the vertical center of each of the chambers 1, 2and 3 from the entrance of the preheating chamber 1 to the exit of thecooling chamber 3 and in a return path arranged at the lower outer sideof the chambers 1, 2 and 3 forming an endless chain conveyor.

Heated gas circulating systems of the same structure are provided aboveand below the conveyor 4 in the preheating chamber 1 and the reflowchamber 2. The system on the upper side is described here, however thesystem on the lower side has an identical structure.

Fans 6 are installed respectively at the upper edge within the chambers1 and 2 as shown in FIG. 1 through FIG. 3. Each of the fans 6 has avertical rotating shaft 6 a and connects to a respective motor 7installed on the upper external side of each of the chambers 1 and 2.The fans 6 are multiblade fans or turbo fans, etc. The fan 6 has anintake opening in the center on the bottom side and a discharge openingon the external circumference, and is housed within a first casingmember 8.

The first casing member 8 (see FIG. 1 through FIG. 5 and FIG. 7) iscomprised of a fan storage section 8 a and a gas guide section 8 b. Thefan storage section 8 a houses the fan 6 and has an intake opening 9 onthe lower surface facing the intake opening of the fan 6. The gas guidesection 8 b extends to a fixed length in one direction from the fanstorage section 8 a and has a width smaller than the diameter of the fan6.

A second casing member 10 (see FIG. 1 through FIG. 4, FIG. 6 and FIG. 7)is installed between the first casing member 8 and the conveyor 4. Thesecond casing member 10 is a rectangular case member as seen from a planview and has a large number of heated gas nozzle holes 11 on the sidefacing the conveyor 4. The width of the second casing member 10 in thetransport line of the conveyor 4 is larger than the width of the gasguide section 8 b of the first casing member 8 and is smaller than thediameter of the fan 6.

In the first casing member 8, the end of the gas guide section 8 b, andthe end on the opposite side from the gas guide section 8 b of the fanstorage section 8 a are connected to both ends of the second casingmember 10 by a duct 12.

The first casing member 8 and the second casing member 10 connected bythe duct 12 are installed in each of the chambers 1 and 2. In this case,the fans 6 are installed with their impeller centers arrayed offset leftand right from the center within the chambers 1 and 2 in a directionperpendicular to the transport line of the conveyor 4. The first casingmember 8 is arranged with the gas guide section 8 b extending in adirection perpendicular to the transport line of the conveyor 4.

In the adjacent chambers 1 and 2, (preheating chamber 1 and preheatingchamber 1, preheating chamber 1 and reflow chamber 2, and reflow chamber2 and reflow chamber 2), the fans 6 are installed in the chambers 1 and2 so that their impeller centers are not on a single perpendicular planealong the transport line of the conveyor 4 and arrayed offset to theleft and right in a direction perpendicular to the transport line of theconveyor 4 in mutually opposite directions from the centers of thechambers 1 and 2. In other words, the fans 6 are arranged left and rightin a zigzag pattern along the transport line of the conveyor 4.

The fan storage sections 8 a of the adjacent first casing members 8 areinstalled to overlap as seen horizontally from a direction perpendicularto the transport line of the conveyor 4. In this embodiment, theadjacent fans 6 also are installed to overlap as seen horizontally froma direction perpendicular to the transport line of the conveyor 4. Inother words, the fan 6 has a diameter larger than the width along thedirection of the transport line of the conveyor 4 in each of thechambers 1 and 2.

Multiple heaters 13 are installed in the space between the first casingmember 8 and the second casing member 10.

A partition wall 14 separating the chambers 1 and 2 is structured asfollows. The partition wall 14 on the upper side is described here,however the partition wall on the lower side is identically formed.

In other words, as shown in FIG. 3 through FIG. 6, a first wall 15separating the first casing members 8 is installed between the adjacentfirst casing members 8 to separate these adjacent first casing members8. The first wall 15 therefore do not extend in a straight lineperpendicular to the transport line of the conveyor 4 but instead extendalong the external side of the first casing member 8 and is thereforecomprised of two straight walls 15 a and 15 b extending in a directionperpendicular to the transport line of the conveyor 4, and a slantedwall 15 c linking these straight walls 15 a and 15 b.

A second wall 16 separating the second casing members 10 is installedbetween the adjacent second casing members 16 to separate these secondcasing members 16. This second wall 16 extends in a straight line in adirection perpendicular to the transport line of the conveyor 4 andintersects the slanted wall 15 c of the first wall 15.

The first wall 15 is installed extending from the upper edge of thechambers 1 and 2 to a position slightly upward from the second casingmember 10, and the second wall 16 is installed below it. The gap betweenthe first wall 15 and the second wall 16 is sealed by a closing wall 17.

The flow of the heated gas is described next.

The nitrogen gas within the chambers 1 and 2 is drawn into the fan 6from the intake opening 9 of the first casing member 8 by the fan 6. Thenitrogen gas is at this time heated while passing through the heater 13.The heated nitrogen gas is discharged from the discharge opening of thefan 6, and enters the second casing member 10 after passing through theduct 12 and the gas guide section 8 b of the first casing member 8, andis blown from the nozzle holes 11 onto the printed circuit board 5mounted with electronic components on the conveyor 4, and the solder onthe printed circuit board is heated. The nitrogen gas then enters aspace 19 between the first casing member 8 and the second casing member10 after passing through a space 18 between the second casing member 10and its surrounding walls, and is drawn into the fan 6 while beingheated by the heater 13 and is discharged to the gas guide section 8 bof the first casing member 8.

The printed circuit board 5 mounted with the electronic components is inthis way gradually heated in the preheating chamber 1 and the solderingpaste melted in the reflow chamber 2. The melted solder on the printedcircuit board 5 mounted with the electronic components is then cooled inthe cooling chamber 3 and the soldering completed.

The fan 6, the first casing member 8 and the second casing member 10 arealso installed in the same way inside the cooling chamber 3.

In this embodiment as described above, the centers of the impellers inthe adjacent fans 6 are not on a single perpendicular plane along thetransport line of the conveyor 4 and alternately arrayed offset to theleft and right. The fans 6 are arrayed left and right in a zigzagpattern along the transport line of the conveyor. The fans 6 having alarger size or in other words greater power can therefore be installedwithout increasing the total length of the reflow soldering apparatus. Areflow soldering apparatus with both superior performance and a compactdesign can therefore be provided.

Another preferred embodiment of the present invention is described nextwhile referring to the accompanying drawings FIG. 8 through FIG. 14.

A reflow soldering apparatus as shown in FIG. 8, is comprised of threepreheating chambers 1, two reflow chambers 2, and one cooling chamber 3which are arrayed in sequence along the transport line of a conveyor 4.Nitrogen gas is supplied into each of the chambers 1, 2 and 3 to preventoxidation of the solder. A printed circuit board 5 mounted withelectronic components is transported in sequence into each of thechambers 1, 2 and 3 by the conveyor 4. After the printed circuit board 5mounted with electronic components is heated at a predeterminedtemperature in the preheating chamber 1, the soldering paste is meltedin the reflow chamber 2, the melted solder then cooled in the coolingchamber 3, and the electronic components soldered onto the printedcircuit board. Nitrogen gas is used in this embodiment to provide thegaseous atmosphere within each of the chambers 1, 2 and 3, however airmay be used as the atmospheric gas.

The conveyor 4 makes a transport line arranged horizontally in a forwardpath in approximately the vertical center of each of the chambers 1, 2and 3 from the entrance of the preheating chamber 1 to the exit of thecooling chamber 3 and in a return path arranged at the lower outer sideof the chambers 1, 2 and 3 forming an endless chain conveyor.

Heated gas circulating systems of the same structure are provided aboveand below the conveyor 4 in the preheating chamber 1 and the reflowchamber 2. The system on the upper side is described here, however thesystem on the lower side has an identical structure.

Fans 6 are installed respectively at the upper edge within the chambers1 and 2 as shown in FIG. 8 through FIG. 10. Each of the fans 6 has avertical rotating shaft 6 a and connects to a respective motor 7installed on the upper external side of each of the chambers 1 and 2.The fans 6 are multiblade fans or turbo fans, etc. The fan 6 has anintake opening in the center on the bottom side and a discharge openingon the external circumference, and is housed within a first casingmember 8.

The first casing member 8 (see FIG. 8 through FIG. 11, FIG. 13 and FIG.14) is comprised of a fan storage section 8 a and a gas guide section 8b. The fan storage section 8 a houses the fan 6 and has an intakeopening 9 on the lower surface facing the intake opening of the fan 6.The gas guide section 8 b extends to a fixed length in both directionsfrom the fan storage section 8 a and has a width smaller than thediameter of the fan 6.

A second casing member 10 (see FIG. 8 through FIG. 10, and FIG. 12through FIG. 14) is installed between the first casing member 8 and theconveyor 4. The second casing member 10 is a rectangular case member asseen from a plan view and has a large number of heated gas nozzle holes11 on the side facing the conveyor 4. The width of the second casingmember 10 in the transport line of the conveyor 4 is larger than thewidth of the gas guide section 8 b of the first casing member 8 and issmaller than the diameter of the fan 6.

In the first casing member 8, the ends of the pair of gas guide sections8 b are connected to both ends of the second casing member 10 by a duct12.

The first casing member 8 and the second casing member 10 connected bythe duct 12 are installed in each of the chambers 1 and 2. The firstcasing member 8 is arranged with the gas guide section 8 b extending ina direction perpendicular to the transport line of the conveyor 4.

In the adjacent chambers 1 and 2, (preheating chamber 1 and preheatingchamber 1, preheating chamber 1 and reflow chamber 2, and reflow chamber2 and reflow chamber 2), the fans 6 are installed in the chambers 1 and2 so that their impeller centers are not on a single horizontal planealong the transport line of the conveyor 4 and alternately arrayedoffset up and down in a direction perpendicular to the transport line ofthe conveyor 4. In other words, the fans 6 are arranged above and belowin a zigzag pattern along the transport line of the conveyor 4.

The second casing member 10 is installed at a fixed height from theconveyor 4, so that the length of the duct 12 connecting the firstcasing member 8 and the second casing member 10 are different in theadjacent chambers 1 and 2.

The fan storage sections 8 a of the adjacent first casing members 8 areinstalled to overlap as seen vertically from a direction perpendicularto the transport line of the conveyor 4. In this embodiment, theadjacent fans 6 also are installed to overlap as seen vertically from adirection perpendicular to the transport line of the conveyor 4. Inother words, the fan 6 has a diameter larger than the width along thedirection of the transport line of the conveyor 4 in each of thechambers 1 and 2.

Multiple heaters 13 are installed in the space between the first casingmember 8 and the second casing member 10.

A partition wall 14 separating the chambers 1 and 2 is installed betweenthe adjacent second casing members 10 to separate these adjacent secondcasing members 8 as shown in FIG. 8, FIG. 9, FIG. 11 and FIG. 12. Thepartition wall 14 extends in a straight line vertically to intersect thetransport line of the conveyor 4. A portion of the fan storage section 8a of the first casing member 8 is arranged in each of the chambers 1 and2 to protrude from the partition wall 14.

The flow of the heated gas is described next.

The nitrogen gas within the chambers 1 and 2 is drawn into the fan 6from the intake opening 9 of the first casing member 8 by the fan 6. Thenitrogen gas is at this time heated while passing through the heater 13.The heated nitrogen gas is discharged from the discharge opening of thefan 6, and enters the second casing member 10 after passing through theduct 12 and the gas guide section 8 b of the first casing member 8, andis blown from the nozzle holes 11 onto the printed circuit board 5mounted with electronic components on the conveyor 4, and the solder onthe printed circuit board is heated. The nitrogen gas then enters aspace 19 between the first casing member 8 and the second casing member10 after passing through a space 18 between the second casing member 10and its surrounding walls, and is drawn into the fan 6 while beingheated by the heater 13 and is discharged to the gas guide section 8 bof the first casing member 8.

The printed circuit board 5 mounted with the electronic components is inthis way gradually heated in the preheating chamber 1 and the solderingpaste melted in the reflow chamber 2. The melted solder on the printedcircuit board 5 mounted with the electronic components is then cooled inthe cooling chamber 3 and the soldering completed.

The fan 6, the first casing member 8 and the second casing member 10 arealso installed in the same way inside the cooling chamber 3.

In this embodiment as described above, the centers of the impellers inthe adjacent fans 6 are not on a single horizontal plane and alternatelyarrayed offset up and down. The fans 6 are arrayed above and below in azigzag pattern along the transport line of the conveyor 4. The fans 6having a larger size or in other words greater power can therefore beinstalled without increasing the total length of the reflow solderingapparatus. A reflow soldering apparatus with both superior performanceand a compact design can therefore be provided.

Another preferred embodiment of the present invention is described nextwhile referring to the accompanying drawings FIG. 15 through FIG. 18.

A reflow soldering apparatus as shown in FIG. 15, is comprised of threepreheating chambers 1, two reflow chambers 2, and one cooling chamber 3which are arrayed in sequence along the transport line of a conveyor 4.Nitrogen gas is supplied into each of the chambers 1, 2 and 3 to preventoxidation of the solder. A printed circuit board 5 mounted withelectronic components is transported in sequence into each of thechambers 1, 2 and 3 by the conveyor 4. After the printed circuit board 5mounted with electronic components is heated at a predeterminedtemperature in the preheating chamber 1, the soldering paste is meltedin the reflow chamber 2, the melted solder then cooled in the coolingchamber 3, and the electronic components soldered onto the printedcircuit board. Nitrogen gas is used in this embodiment to provide thegaseous atmosphere within each of the chambers 1, 2 and 3, however airmay be used as the atmospheric gas.

The conveyor 4 makes a transport line arranged horizontally in a forwardpath in approximately the vertical center of each of the chambers 1, 2and 3 from the entrance of the preheating chamber 1 to the exit of thecooling chamber 3 and in a return path arranged at the lower outer sideof the chambers 1, 2 and 3 forming an endless chain conveyor.

Heated gas circulating systems of the same structure are provided aboveand below the conveyor 4 in the preheating chamber 1 and the reflowchamber 2. The system on the upper side is described here, however thesystem on the lower side has an identical structure.

Fans 6 are installed respectively at the side within the chambers 1 and2 as shown in FIG. 15 through FIG. 17. Each of the fans 6 has ahorizontal rotating shaft 6 a and connects to a respective motor 7installed on the external side of each of the chambers 1 and 2. The fans6 are multiblade fans or turbo fans, etc. The fan 6 has an intakeopening in the center facing the inner side in each of the chambers 1and 2 and a discharge opening on the external circumference, and ishoused within a first casing member 8.

In the adjacent chambers 1 and 2, (preheating chamber 1 and preheatingchamber 1, preheating chamber 1 and reflow chamber 2, and reflow chamber2 and reflow chamber 2), the fans 6 are installed in mutually oppositeside on the left and right to the transport line. In other words, thefans 6 are installed in the chambers 1 and 2 so that their impellercenters are not on a single perpendicular plane along the transport lineof the conveyor 4 and alternately arrayed offset to the left and rightin a direction perpendicular to the transport line of the conveyor 4.The fans 6 are arranged left and right in a zigzag pattern along thetransport line of the conveyor 4.

The first casing member 8 (see FIG. 16 through FIG. 18) is comprised ofa fan storage section 8 a and a gas guide section 8 b. The fan storagesection 8 a houses the fan 6 and has an intake opening 9 on the surfacefacing the intake opening of the fan 6. The gas guide section 8 bextends from the upper edge of the fan storage section 8 a toward thecenter section in each of the chambers 1 and 2.

A second casing member 10 (see FIG. 15 through FIG. 18) is installedabove the conveyor 4. The second casing member 10 is a rectangular casemember as seen from a plan view and has a large number of heated gasnozzle holes 11 on the side facing the conveyor 4. The width of thesecond casing member 10 in the transport line of the conveyor 4 issmaller than the diameter of the fan 6.

The end of the gas guide section 8 b in the first casing member 8 isconnected to the upper surface center section of the second casingmember 10 by a duct 12.

The fan storage sections 8 a of the adjacent first casing members 8 areinstalled to overlap as seen horizontally from a direction perpendicularto the transport line of the conveyor 4. In this embodiment, theadjacent fans 6 also are installed to overlap as seen horizontally froma direction perpendicular to the transport line of the conveyor 4. Inother words, the fan 6 has a diameter larger than the width along thedirection of the transport line of the conveyor 4 in each of thechambers 1 and 2.

Multiple heaters 13 are installed in the space located forward of theintake opening 9 in the first casing member 8.

A partition wall 14 separating the chambers 1 and 2 is installed betweenthe adjacent second casing members 10 as shown in FIG. 15 and FIG. 16.The partition wall 14 extends vertically in a straight lineperpendicular to the transport line of the conveyor 4. In the chambers 1and 2, a small chamber 20 containing the fan storage section 8 a of thefirst casing member 8 is formed to protrude on the side of the secondcasing member 10. The small chambers 20 are formed on one side of thechambers 1 and 2 respectively, and are arranged on the opposite side toeach other in the adjacent chambers 1 and 2.

The flow of the heated gas is described next.

The nitrogen gas within the chambers 1 and 2 is drawn into the fan 6from the intake opening 9 of the first casing member 8 by the fan 6. Thenitrogen gas is at this time heated while passing through the heater 13.The heated nitrogen gas is discharged from the discharge opening of thefan 6, and enters the second casing member 10 after passing through theduct 12 and the gas guide section 8 b of the first casing member 8, andis blown from the nozzle holes 11 onto the printed circuit board 5mounted with electronic components on the conveyor 4, and the solder onthe printed circuit board is heated. The nitrogen gas then passesthrough a space 18 between the second casing member 10 and itssurrounding walls, and is drawn into the fan 6 while being heated by theheater 13 and is discharged to the gas guide section 8 b of the firstcasing member 8.

The printed circuit board 5 mounted with the electronic components is inthis way gradually heated in the preheating chamber 1 and the solderingpaste melted in the reflow chamber 2. The melted solder on the printedcircuit board 5 mounted with the electronic components is then cooled inthe cooling chamber 3 and the soldering completed.

The fan 6, the first casing member 8 and the second casing member 10 arealso installed in the same way inside the cooling chamber 3.

In this embodiment as described above, the centers of the impellers inthe adjacent fans 6 are not on a single perpendicular plane along thetransport line of the conveyor 4 and alternately arrayed offset to theleft and right. The fans 6 are arrayed left and right in a zigzagpattern along the transport line of the conveyor 4. The fans 6 having alarger size or in other words greater power can therefore be installedwithout increasing the total length of the reflow soldering apparatus. Areflow soldering apparatus with both superior performance and a compactdesign can therefore be provided.

In this embodiment, the fans are installed on the opposite side to eachother in the adjacent chambers. However, the fans may all be installedon the same side and may be arrayed left and right or above and below ina zigzag pattern as described in the first and second embodiments.

Another preferred embodiment of the present invention is described nextwhile referring to the accompanying drawings FIG. 19 through FIG. 23.

A reflow soldering apparatus as shown in FIG. 19, is comprised of threepreheating chambers 1, two reflow chambers 2, and one cooling chamber 3which are arrayed in sequence along the transport line of a conveyor 4.Nitrogen gas is supplied into each of the chambers 1, 2 and 3 to preventoxidation of the solder. A printed circuit board 5 mounted withelectronic components is transported in sequence into each of thechambers 1, 2 and 3 by the conveyor 4. After the printed circuit board 5mounted with electronic components is heated at a predeterminedtemperature in the preheating chamber 1, the soldering paste is meltedin the reflow chamber 2, the melted solder then cooled in the coolingchamber 3, and the electronic components soldered onto the printedcircuit board. Nitrogen gas is used in this embodiment to provide thegaseous atmosphere within each of the chambers 1, 2 and 3, however airmay be used as the atmospheric gas.

The conveyor 4 makes a transport line arranged horizontally in a forwardpath in approximately the vertical center of each of the chambers 1, 2and 3 from the entrance of the preheating chamber 1 to the exit of thecooling chamber 3 and in a return path arranged at the lower outer sideof the chambers 1, 2 and 3 forming an endless chain conveyor.

Heated gas circulating systems of the same structure are provided aboveand below the conveyor 4 in the preheating chamber 1 and the reflowchamber 2. The system on the upper side is described here, however thesystem on the lower side has an identical structure.

Fans 6 are installed respectively at the upper edge within the chambers1 and 2 as shown in FIG. 19 through FIG. 21. Each of the fans 6 connectsto a respective motor 7 installed on the upper external side of each ofthe chambers 1 and 2. The fans 6 are arranged in a inclined position. Inother words, in this embodiment, the fans 6 are arranged with theirrotating shafts 6 a inclined along the forward direction of progressionof the transport line of the conveyor 4. The upper wall of the chambers1 and 2 that the rotating shaft 6 a of the fan 6 passes through is adiagonal wall, and the motor 7 is installed in a inclined position onthe upper surface of the upper wall. The fans 6 are multiblade fans orturbo fans, etc. The fan 6 has an intake opening in the center on thebottom side and a discharge opening on the external circumference, andis housed within a first casing member 8.

The first casing member 8 (see FIG. 19 through FIG. 22) is comprised ofa fan storage section 8 a and a gas guide section 8 b. The fan storagesection 8 a houses the fan 6 and has an intake opening 9 on the lowersurface facing the intake opening of the fan 6. The gas guide section 8b extends to a fixed length in both directions from the fan storagesection 8 a and has a width smaller than the diameter of the fan 6. Thefirst casing member 8 is also arranged diagonally at the same inclinedangle as the fan 6.

A second casing member 10 (see FIG. 19 through FIG. 22) is installedbetween the first casing member 8 and the conveyor 4. The second casingmember 10 is a rectangular case member as seen from a plan view andinstalled horizontally. The second casing member 10 has a large numberof heated gas nozzle holes 11 on the side facing the conveyor 4.

In the first casing member 8, the ends of the pair of gas guide sections8 b are connected to both ends of the second casing member 10 by a duct12.

The first casing member 8 and the second casing member 10 connected bythe duct 12 are installed in each of the chambers 1 and 2. In this case,The first casing member 8 is arranged with the gas guide section 8 bextending in a direction perpendicular to the transport line of theconveyor 4.

The diameter of the fan 6 is larger than the width along the transportline of the conveyor 4 in each of the chambers 1 and 2.

Multiple heaters 13 are installed in the space between the first casingmember 8 and the second casing member 10.

A partition wall 14 separating the chambers 1 and 2 extends verticallyin a straight line perpendicular to the transport line of the conveyor4.

The flow of the heated gas is described next.

The nitrogen gas within the chambers 1 and 2 is drawn into the fan 6from the intake opening 9 of the first casing member 8 by the fan 6. Thenitrogen gas is at this time heated while passing through the heater 13.The heated nitrogen gas is discharged from the discharge opening of thefan 6, and enters the second casing member 10 after passing through theduct 12 and the gas guide section 8 b of the first casing member 8, andis blown from the nozzle holes 11 onto the printed circuit board 5mounted with electronic components on the conveyor 4, and the solder onthe printed circuit board is heated. The nitrogen gas then enters aspace 19 between the first casing member 8 and the second casing member10 after passing through a space 18 between the second casing member 10and its surrounding walls, and is drawn into the fan 6 while beingheated by the heater 13 and is discharged to the gas guide section 8 bof the first casing member 8.

The printed circuit board 5 mounted with the electronic components is inthis way gradually heated in the preheating chamber 1 and the solderingpaste melted in the reflow chamber 2. The melted solder on the printedcircuit board 5 mounted with the electronic components is then cooled inthe cooling chamber 3 and the soldering completed.

The fan 6, the first casing member 8 and the second casing member 10 arealso installed in the same way inside the cooling chamber 3.

In this embodiment, the fans 6 are arranged in a inclined position asdescribed above, so that the fans 6 having a larger size or in otherwords greater power can therefore be installed without increasing thetotal length of the reflow soldering apparatus. A reflow solderingapparatus with both superior performance and a compact design cantherefore be provided.

The example in the embodiment shows the rotating shafts 6 a of the fans6 arranged diagonally in different directions. However, as shown in FIG.23, the rotating shafts 6 a of the upper and lower fans 6 may bearranged diagonally in the same direction.

The example in the embodiment shows the rotating shafts of the fansarranged diagonally along the transport line of the conveyor. However,the inclined direction of the rotating shafts of the fans may be tiltedin a direction to form an angle with the transport line of the conveyor.

There are no particular restrictions on the inclined angle of therotating shaft of the fan and the rotating shaft may for example bearranged at 90 degrees or in others words in a horizontal position, etc.

INDUSTRIAL APPLICABILITY

The present invention as described above can provide a reflow solderingapparatus with both superior performance and a compact design, so thatthe space for installing an apparatus can be made small and the reflowsoldering apparatus of the present invention is therefore effective forsoldering of the electronic components on the circuit boards.

1. A reflow soldering apparatus comprising a conveyor to transportcircuit boards mounted with electronic components into multiplechambers, and blowing means installed in said chambers, wherein thecenters of the impellers in said adjacent blowing means are not on asingle perpendicular plane along a transport line of said conveyor andarrayed offset to the left and right.
 2. A reflow soldering apparatus asclaimed in claim 1, wherein said blowing means are arrayed left andright in a zigzag pattern along the transport line of said conveyor. 3.A reflow soldering apparatus comprising a conveyor to transport circuitboards mounted with electronic components into multiple chambers, andblowing means installed in said chambers, wherein the centers of theimpellers in said adjacent blowing means are not on a single horizontalplane and arrayed offset up and down.
 4. A reflow soldering apparatus asclaimed in claim 3, wherein said blowing means are arrayed above andbelow in a zigzag pattern along the transport line of said conveyor. 5.A reflow soldering apparatus comprising a conveyor to transport circuitboards mounted with electronic components into multiple chambers, andblowing means installed in said chambers, wherein said blowing means arearranged with their rotating shafts inclined in said chambers.
 6. Areflow soldering apparatus as claimed in claim 5, wherein said blowingmeans are installed above and below said conveyor, and the rotatingshafts of said upper and lower blowing means are arranged diagonally indifferent directions.
 7. A reflow soldering apparatus as claimed inclaim 5, wherein said blowing means are installed above and below saidconveyor, and the rotating shafts of said upper and lower blowing meansare arranged diagonally in the same direction.